As well known, OFDM is sensitive to synchronization errors. In OFDM-based concurrent cooperative transmission (CCT), because of its distributed nature, the synchronization of the system is much more difficult. This project is expected to give some effective and simple methods to solve the synchronization problems in CCT, including carrier frequency offset (CFO) synchronization, sampling frequency offset (SFO) synchronization, timing synchronization, and other impairment problems for traditional OFDM systems. We are taking a transmit pre-synchronization approach, rather than trying to compensate all offsets in the receiver signal processor, to facilitate sequential cluster-to-cluster transmissions. Finally, we intend to implement our schemes on the SDR testbed. Figure below shows some preliminary simulation results for the second hop in a “source-cluster-destination” topology. Nq is the number of relays in the cluster and Nb is the packet length.
